Entity Documentation - minecraft:genetics

minecraft:genetics defines the way a mob's genes and alleles are passed on to its offspring, and how those traits manifest in the child. Compatible parent genes are crossed together, the alleles are handed down from the parents to the child, and any matching genetic variants initiate JSON events to modify the child and express the traits.

Parameters

Name	Default Value	Type	Description
genes	not set	List	The list of genes that this entity has and will cross with a partner during breeding.
mutation_rate	0.03125	Decimal	Chance that an allele will be replaced with a random one instead of the parent's allele during birth.
use_simplified_breeding	--	Boolean	When set to 'true', this optional flag prohibits the inheritance of hidden parent alleles as main alleles in children and the inheritance of main alleles as hidden alleles in children. This allows for easier implementation of basic breeding logic.

genes

genes is a list defined by three parameters. Each item has the following properties:

Name	Default Value	Type	Description
allele_range	not set	Integer	The range of positive integer allele values for this gene. Spawned mobs will have a random number in this range assigned to them.
genetic_variants	not set	List	The list of genetic variants for this gene. These check for particular allele combinations and initiate events when all of them are satisfied.
name	not set	String	The name of the gene.

allele_range

allele_range is an integer defined by two parameters. Each item has the following properties:

Name	Default Value	Type	Description
range_max	0	Integer	Upper bound of the allele values for this gene.
range_min	0	Integer	Lower bound of the allele values for this gene.

genetic_variants

genetic_variants is a decimal defined by five parameters. Each item has the following properties:

Name	Default Value	Type	Description
birth_event	not set	JSON Object	Event to run when this mob is created and matches the allele conditions.
both_allele	-1	Integer	If this value is non-negative, compare both the mob's main and hidden alleles with this value for a match with both. Can also be a range of integers.
either_allele	-1	Integer	If this value is non-negative, compare both the mob's main and hidden alleles with this value for a match with either. Can also be a range of integers.
hidden_allele	-1	Integer	If this value is non-negative, compare the mob's hidden allele with this value for a match. Can also be a range of integers.
main_allele	-1	Integer	If this value is non-negative, compare the mob's main allele with this value for a match. Can also be a range of integers.
mutation_rate	-1	Decimal	If this value is non-negative, overrides the chance for this gene that an allele will be replaced with a random one instead of the parent's allele during birth. Non-negative values greater than 1 will be the same as the value 1.

Example

"minecraft:genetics":{
    "genes": [
        {
            "allele_range": {
                "range_max": 0,
                "range_min": 0,
            },
            "genetic_variants": [
                {
                    "birth_event": {
                      "event": "minecraft:born_screamer",
                      "target": "self"
                    },                    
                    "main_allele": {
                      "range_min": 1,
                      "range_max": 2
                    }
                }
            ],
            "name": "gene",
        }
    ],
    "mutation_rate": 0.03125
}

Vanilla entities examples

panda

"mutation_rate": 0.03125,
        "genes": [
          {
            "name": "panda_variant",
            "allele_range": {
              "range_min": 0,
              "range_max": 15
            },
            "genetic_variants": [
              {
                "main_allele": 0,
                "birth_event": {
                  "event": "minecraft:panda_lazy",
                  "target": "self"
                }
              },
              {
                "main_allele": 1,
                "birth_event": {
                  "event": "minecraft:panda_worried",
                  "target": "self"
                }
              },
              {
                "main_allele": 2,
                "birth_event": {
                  "event": "minecraft:panda_playful",
                  "target": "self"
                }
              },
              {
                "main_allele": 3,
                "birth_event": {
                  "event": "minecraft:panda_aggressive",
                  "target": "self"
                }
              },
              {
                "both_allele": {
                  "range_min": 4,
                  "range_max": 7
                },
                "birth_event": {
                  "event": "minecraft:panda_weak",
                  "target": "self"
                }
              },
              {
                "both_allele": {
                  "range_min": 8,
                  "range_max": 9
                },
                "birth_event": {
                  "event": "minecraft:panda_brown",
                  "target": "self"
                }
              }
            ]
          }
        ]

Vanilla entities using minecraft:genetics

• goat
• panda